Light puttering under idle

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[TehWinGTP]

Doesn't buck have a late model 3800 powered lumina that he replaced the lim gaskets and uim on, and also had the transmission rebuilt? IIRC he bought it less than half a year ago, so in essence he does have a 3800.

Buck, I hope you didn't pay too much for that LQ1 car. I haven't been keeping too much track of your cars lately, but a burned valve is only going to get worse.

A valve burns for many reasons, but the short story is that the valve doesn't seat properly under a high load. An exahust valve runs at 1300 degrees F normally. While the intake valve is cooled by the incoming air, 75% of the exhaust valve's cooling is done when the cylinder head  absorbs the heat through the valve seat. There are a vast number of reasons why a valve would not seat properly, but once the valve burns, the valve can either crack, chip, or simply make a horrible contact with the head, and that's something that will only continue to get worse. Because one or more valves is not making a good seal anymore, you will lose compression in those cylinders, which means your engine will run rougher, and your performance and fuel economy will drop.

At this point I'm doubting if it would be worth it for you to get the issue fixed, but I'm also doubting if it would be worth it for you to keep it. I would sell it while it still runs.

I'm fixing my problem by replacing the heads with low mileage (85k mile) heads off an engine as noted earlier, but my Regal also isn't one that I could run to the ground because of a burned valve.

3800 powered car was a Monte z34, and Kenny drives it now.

This LQ1 HAULS ASS, Is it supposed to haul more ass or something?

And I have two spare lq1 heads, I figure I could replace the exhaust valves and be good to go

[Chris]

I wonder if that's the problem with my girlfriends piece of shit. It's more than a "light puttering", like a "heavy puttering" haha. That probably wouldn't cause it's random stalling problem though

[TehWinGTP]

I wonder if that's the problem with my girlfriends piece of shit. It's more than a "light puttering", like a "heavy puttering" haha. That probably wouldn't cause it's random stalling problem though

Yeah same here. It seems almost like a misfire at times.

I also have a high idle problem

[3.1cutlass]

I haven't done a compression test myself, but I'm also fairly sure that I do indeed have a bad valve. Ring wear would not cause the kind of puttering I'm hearing here, plus the dollar bill trick, and if my rings were worn that badly, I would imagine I'd be losing a significant amount of oil, which I'm not.

If it turns out I do have ring or piston damage, it will give me a reason to swap in the much stronger S1 L67 rods and pistons with new rings, and I'll have a second pair of heads for porting.

Compression test would confirm the valve. I said it on w-body and i will here too. Just be aware this could also be caused by a misfire, valves out of adjustment, or bad compression. Its not a sure fire test that it IS a burnt valve. I would check things like plugs, wires, and coils and have a compression test done before you are sure its a valve. Compression test could confirm a burnt valve.

[SofaKingWeToddDid]

Compression test would confirm the valve. I said it on w-body and i will here too. Just be aware this could also be caused by a misfire, valves out of adjustment, or bad compression. Its not a sure fire test that it IS a burnt valve. I would check things like plugs, wires, and coils and have a compression test done before you are sure its a valve. Compression test could confirm a burnt valve.

wont bad rings take out compression too?

[XTRevolution]

3800 powered car was a Monte z34, and Kenny drives it now.

This LQ1 HAULS ASS, Is it supposed to haul more ass or something?

And I have two spare lq1 heads, I figure I could replace the exhaust valves and be good to go

When a valve burns, it often wears out the valve guide as well, and possibly the seat too. Replacing a valve without fixing the reason why it burned in the first place and replacing other wear items around the valve will guarantee you another burned valve. Why not just replace the heads with good ones and be done with it?

Of course, in my situation, I'm sure its a burned valve simply because my injectors and plugs are new, and valves don't just fall out of alignment that badly in 200k miles. Bad compression could be caused by a lot of things, one of which is a burned valve. Has anyone here seen bad rings on an LQ1 or 3800 by 200k miles? I haven't. Granted a leak-down test would confirm if you do have bad rings, but I'm doubting that's your problem. You'd be burning a lot of oil if it was, and I know for a fact I'm not burning any oil. The same amount of oil comes out of my engine after 3000 miles as I put in there every oil change.

Don't get me wrong Buck, my 3800 hauls ass too, but you can definitely tell something's not quite right, and the fact that its only going to get worse if it is a burned valve is why I would advise finding out what the problem is.

[3.1cutlass]

wont bad rings take out compression too?

Correct. Since any w-body motor rarely burns out rings compression would confirm a burnt valve.

[Prospeeder]

Well. you can have bad compression rings but still have good oil control rings. So no low compression from rings wouldnt mean oil consumption. And a compression test would tell you what cylinder is bad, then a leakdown would be able to pinpoint intake or exhaust. Valves burn for a number of reason. I was aware its more of an OLD pre 80's car thing. But if you detonate, forien material chips/nicks valve, somthing to slightly damage the valve sealing to the seat, the valve quickly overheats because it dissapates the heat through the seat and if a part isnt touching the seat, it overheats and burns and just goes from there. you would definatly feel more than just putter, it would quickly burn away the valve till there was 0 compression and you would have a dead miss.

[XTRevolution]

Well. you can have bad compression rings but still have good oil control rings. So no low compression from rings wouldnt mean oil consumption. And a compression test would tell you what cylinder is bad, then a leakdown would be able to pinpoint intake or exhaust. Valves burn for a number of reason. I was aware its more of an OLD pre 80's car thing. But if you detonate, forien material chips/nicks valve, somthing to slightly damage the valve sealing to the seat, the valve quickly overheats because it dissapates the heat through the seat and if a part isnt touching the seat, it overheats and burns and just goes from there. you would definatly feel more than just putter, it would quickly burn away the valve till there was 0 compression and you would have a dead miss.

How long do you figure oil seal rings would last once compression rings start to go? I think they're meant to work together, and oil seal rings aren't intended to hold compression. If they don't hold compression, I don't see how they'll hold the oil for too long once compression rings are bad. The compression rings are also there to keep pressure from going against the oil seal rings. The moment you start moving away from TDC, that suction will pull up oil pretty easily.

In any case, I'll do a compression and leak-down test on my motor just to be 100% sure, but I've got a pretty good feeling the valve is burned. If the valve wasn't burned, your exahust pipe wouldn't be sucking up a dollar bill, because you wouldn't have any leaks on the exhaust valves when the piston moves away from TDC and creates suction. IMO a dollar bill test is a 100% sure way to tell that you have exhaust valve problems. How else do you figure you can create suction in the exhaust pipe that wouldn't be related to an exhaust valve?

[SofaKingWeToddDid]

Correct. Since any w-body motor rarely burns out rings compression would confirm a burnt valve.

LQ1 included?

[3.1cutlass]

How long do you figure oil seal rings would last once compression rings start to go? I think they're meant to work together, and oil seal rings aren't intended to hold compression. If they don't hold compression, I don't see how they'll hold the oil for too long once compression rings are bad. The compression rings are also there to keep pressure from going against the oil seal rings. The moment you start moving away from TDC, that suction will pull up oil pretty easily.

In any case, I'll do a compression and leak-down test on my motor just to be 100% sure, but I've got a pretty good feeling the valve is burned. If the valve wasn't burned, your exahust pipe wouldn't be sucking up a dollar bill, because you wouldn't have any leaks on the exhaust valves when the piston moves away from TDC and creates suction. IMO a dollar bill test is a 100% sure way to tell that you have exhaust valve problems. How else do you figure you can create suction in the exhaust pipe that wouldn't be related to an exhaust valve?

Like I said a misfire can cause this as well.

[XTRevolution]

Like I said a misfire can cause this as well.

Please explain to me how a misfire with perfectly sealing intake and exhaust valves will cause negative pressure in the exhaust pipe.

[TehWinGTP]

Please explain to me how a misfire with perfectly sealing intake and exhaust valves will cause negative pressure in the exhaust pipe.

What he said.






I will say though that my LQ1 DOES burn oil..... But I thought they all did lol

[Prospeeder]

Theres a difference between burning oil and leaking it. And Im very sure  no GM v6 burns oil unless thier hammered hard with no oil changes. These are the leakiest engines, even if you dont see drips

[XTRevolution]

Theres a difference between burning oil and leaking it. And Im very sure  no GM v6 burns oil unless thier hammered hard with no oil changes. These are the leakiest engines, even if you dont see drips

I agree with this statement. I know for a fact my regal leaks and I can see the spots in the garage which is now covered by a few layers of cardboard.